ICT Sustainability", is popular with students and got me an award from my peers.
When I am producing audio I use a USB Headset. This puts the microphone close to the mouth and the audio is digitized in the headset, which improves the quality. MP3 is fine for the audio format.
If you are recording with a live audience, see if your institution has a built in recording option. The Australian National University has lecture theaters equipped with a recording system which takes the audio from the room PA system and the video from the main screen. This saves having to worry about a separate microphone. I just have to remember to press "Record" at the start and "Stop" at the end and a podcast is produced. The ANU system is called the Digital Lecture Delivery Service and many universities have similar facilities.